From 7a4d4de8a87f3dca6870e79e4110d8e3ecd7385b Mon Sep 17 00:00:00 2001 From: dianne Date: Tue, 1 Apr 2025 21:35:12 -0700 Subject: [PATCH] add tests for array/slice const patterns --- .../const_in_pattern/arrays-and-slices.rs | 53 ++++++++++++ .../const_in_pattern/arrays-and-slices.stderr | 84 +++++++++++++++++++ 2 files changed, 137 insertions(+) create mode 100644 tests/ui/consts/const_in_pattern/arrays-and-slices.rs create mode 100644 tests/ui/consts/const_in_pattern/arrays-and-slices.stderr diff --git a/tests/ui/consts/const_in_pattern/arrays-and-slices.rs b/tests/ui/consts/const_in_pattern/arrays-and-slices.rs new file mode 100644 index 000000000000..bb38490206b2 --- /dev/null +++ b/tests/ui/consts/const_in_pattern/arrays-and-slices.rs @@ -0,0 +1,53 @@ +//! Tests that arrays and slices in constants aren't interchangeable when used as patterns. + +#[derive(PartialEq, Eq)] +struct SomeStruct(T); + +const BSTR_SIZED: &'static [u8; 3] = b"012"; +const BSTR_UNSIZED: &'static [u8] = BSTR_SIZED; +const STRUCT_SIZED: &'static SomeStruct<[u8; 3]> = &SomeStruct(*BSTR_SIZED); +const STRUCT_UNSIZED: &'static SomeStruct<[u8]> = STRUCT_SIZED; + +fn type_mismatches() { + // Test that array consts can't be used where a slice pattern is expected. This helps ensure + // that `const_to_pat` won't produce irrefutable `thir::PatKind::Array` patterns when matching + // on slices, which would result in missing length checks. + // See also `tests/ui/match/pattern-deref-miscompile.rs`, which tests that byte string literal + // patterns check slices' length appropriately when matching on slices. + match BSTR_UNSIZED { + BSTR_SIZED => {} + //~^ ERROR: mismatched types + _ => {} + } + match STRUCT_UNSIZED { + STRUCT_SIZED => {} + //~^ ERROR: mismatched types + _ => {} + } + + // Test that slice consts can't be used where an array pattern is expected. + match BSTR_UNSIZED { + BSTR_SIZED => {} + //~^ ERROR: mismatched types + _ => {} + } + // If the types matched here, this would still error, since unsized structs aren't permitted in + // constant patterns. See the `invalid_patterns` test below. + match STRUCT_UNSIZED { + STRUCT_SIZED => {} + //~^ ERROR: mismatched types + _ => {} + } +} + +fn invalid_patterns() { + // Test that unsized structs containing slices can't be used as patterns. + // See `tests/ui/consts/issue-87046.rs` for an example with `str`. + match STRUCT_UNSIZED { + STRUCT_UNSIZED => {} + //~^ ERROR: cannot use unsized non-slice type `SomeStruct<[u8]>` in constant patterns + _ => {} + } +} + +fn main() {} diff --git a/tests/ui/consts/const_in_pattern/arrays-and-slices.stderr b/tests/ui/consts/const_in_pattern/arrays-and-slices.stderr new file mode 100644 index 000000000000..412caf60f7d8 --- /dev/null +++ b/tests/ui/consts/const_in_pattern/arrays-and-slices.stderr @@ -0,0 +1,84 @@ +error[E0308]: mismatched types + --> $DIR/arrays-and-slices.rs:18:9 + | +LL | const BSTR_SIZED: &'static [u8; 3] = b"012"; + | ---------------------------------- constant defined here +... +LL | match BSTR_UNSIZED { + | ------------ this expression has type `&[u8]` +LL | BSTR_SIZED => {} + | ^^^^^^^^^^ + | | + | expected `&[u8]`, found `&[u8; 3]` + | `BSTR_SIZED` is interpreted as a constant, not a new binding + | help: introduce a new binding instead: `other_bstr_sized` + | + = note: expected reference `&[u8]` + found reference `&'static [u8; 3]` + +error[E0308]: mismatched types + --> $DIR/arrays-and-slices.rs:23:9 + | +LL | const STRUCT_SIZED: &'static SomeStruct<[u8; 3]> = &SomeStruct(*BSTR_SIZED); + | ------------------------------------------------ constant defined here +... +LL | match STRUCT_UNSIZED { + | -------------- this expression has type `&SomeStruct<[u8]>` +LL | STRUCT_SIZED => {} + | ^^^^^^^^^^^^ + | | + | expected `&SomeStruct<[u8]>`, found `&SomeStruct<[u8; 3]>` + | `STRUCT_SIZED` is interpreted as a constant, not a new binding + | help: introduce a new binding instead: `other_struct_sized` + | + = note: expected reference `&SomeStruct<[u8]>` + found reference `&'static SomeStruct<[u8; 3]>` + +error[E0308]: mismatched types + --> $DIR/arrays-and-slices.rs:30:9 + | +LL | const BSTR_SIZED: &'static [u8; 3] = b"012"; + | ---------------------------------- constant defined here +... +LL | match BSTR_UNSIZED { + | ------------ this expression has type `&[u8]` +LL | BSTR_SIZED => {} + | ^^^^^^^^^^ + | | + | expected `&[u8]`, found `&[u8; 3]` + | `BSTR_SIZED` is interpreted as a constant, not a new binding + | help: introduce a new binding instead: `other_bstr_sized` + | + = note: expected reference `&[u8]` + found reference `&'static [u8; 3]` + +error[E0308]: mismatched types + --> $DIR/arrays-and-slices.rs:37:9 + | +LL | const STRUCT_SIZED: &'static SomeStruct<[u8; 3]> = &SomeStruct(*BSTR_SIZED); + | ------------------------------------------------ constant defined here +... +LL | match STRUCT_UNSIZED { + | -------------- this expression has type `&SomeStruct<[u8]>` +LL | STRUCT_SIZED => {} + | ^^^^^^^^^^^^ + | | + | expected `&SomeStruct<[u8]>`, found `&SomeStruct<[u8; 3]>` + | `STRUCT_SIZED` is interpreted as a constant, not a new binding + | help: introduce a new binding instead: `other_struct_sized` + | + = note: expected reference `&SomeStruct<[u8]>` + found reference `&'static SomeStruct<[u8; 3]>` + +error: cannot use unsized non-slice type `SomeStruct<[u8]>` in constant patterns + --> $DIR/arrays-and-slices.rs:47:9 + | +LL | const STRUCT_UNSIZED: &'static SomeStruct<[u8]> = STRUCT_SIZED; + | ----------------------------------------------- constant defined here +... +LL | STRUCT_UNSIZED => {} + | ^^^^^^^^^^^^^^ + +error: aborting due to 5 previous errors + +For more information about this error, try `rustc --explain E0308`.